The present invention relates generally to a valve, and more particularly to a pressure-reducing valve. Still more specifically, the invention relates to a pressure-reducing valve wherein the response pressure of a main valve can be controlled by setting of a control valve.
Pressure regulating valves of this type are already known. However, they have certain disadvantages, at least under some operating circumstances. In particular, if large relatively compressible fluid volumes are active upon the controlled low pressure side of the valve, which require relatively substantial compression in the case of pressure variations, the prior-art valves will not be properly responsive. For example, if the response pressure which has been preselected with the control valve is dropped rapidly, the pressure at the lower sides will follow this change only very slowly, because when the main valve is closed the compression volume at the low pressure side can be discharged only via the control oil flow of the control valve. Since further the main valve has a positive overlap when its valve member is in blocking position, pressure oscillations occur at the low pressure side which may be substantial as to frequency and amplitude; these oscillations are usually found to be disturbing or unacceptable.